Method of removing static electricity from paper, yarn, &amp;c.



No. 777,598. PATENTED DEC. 13, 1904.

' W. H. CIIAPMAN. METHOD OF REMOVING STATIC ELECTRICITY FROM PAPER,YARN, 6x0.

APPLICATION FILED JAN. 25, 1904.

. 7) S535: Iyr/ea) [0 UNITED STATES Patented December 13, 1904.

PATENT OFFICE.

WILLIAM H. CHAPMAN,

LAND COMPANY, OF PORTLAND, MAINE,

OF PORTLAND, MAINE, ASSIGNOR TO THE PORT- A CORPORATION OF MAINE.

SPECIFICATION forming part of Letters Patent No. 777,598, dated.December 13, 1904. Application filed January 25, 1904. Serial No.190,451. (No model.)

To all whom it may concern:

Be it known that 1, WILLIAM H. CHAPMAN, a

4 citizen of the United States of America, and a resident of Portland,Cumberland county, State of Maine, have invented certain new and usefulImprovements in Methods of Removing Static Electricity from Paper, Yarn,&c., of which the following is a specification.

My invention relates to a method of removing static electricity frompaper, yarn, and other like articles which during their manufacture ormanipulation become charged with such electrity.

Static electricity generated by friction and by the separation ofsurfaces is often the source of great annoyance and delay in theoperation of various kinds of machinery-as, for instance, in thecalenders of paper-machines, in printing-presses, and in the machineryfor working different kinds of fabrics-and it becomes of greatimportance to neutralize these static charges in order that themachinery may be worked in an eflicient manner and at a desirable rateof speed. In the handling of paper the sheets of paper stick to eachother and to other surfaces, causing breakage and delay, and to preventthese difficulties a variety of devices have been tried in the past withunsatisfactory results. Steam-jets have been used to some extent toconduct away the static charge, and metallicconduptors studded withnumerous sharp points presented to the charged surfaces and connected bywire to the earth have also been used; but these methods while partiallysuccessful and somewhat useful'do not remove the whole charge and enoughremains to cause a great deal of trouble. The method of my presentinvention, however, completely takes away all of the static charge,leaving the paper or fabric perfectly neutral.

It is a well-known principle of static elec- I tricity that a chargedbody of small surface,

like a wire or a body with projecting points, discharges its electricityinto the surrounding air more readily than one of a large surface andsmooth, and charges are thus delivered to other bodies in the vicinityof it by a slow the alternating charge,

kind of conduction, sometimes called convection. Now if the charged bodyof small surface or having projecting points is all the while of onepolarity and another body be placed in a fixed position'near it thesecond body will slowly acquire acharge of the same polarity as thefirst one, even though it previously had a charge of opposite sign. If,however, the second body instead of being retained in one position ofproximity to the charged body be moved past it, coming gradually to theposition of proximity and then receding from it, 'a previously-existingcharge of opposite polarity in the second body will become entirelyneutralized and the body will pass away in a neutral condition, providedthe point termed the position of proximity be properly chosen withreference to the speed of the movement and the potential of the chargeexisting on the first-named charged body. On the other hand, when analternating charge is used for the purpose the charges becomeself-selective and tend to a condition of neutrality for the secondbody, which becomes the stable condition for that body, as will beapparent by the following considerations, whether the body be at rest orin motion: Let us assume the second body to be positively charged andplaced in a fixed position near a fine wire having an alternatingcharge. tive impulses of the alternating charge to pass over to thesecond body becomes much greater than the tendency of the positiveimpulses to pass over until the body is reduced to neutrality, when abalance is arrived at between the two; but whatever polarity the secondbody may have it creates for itself a tendency to neutralize in thepresence of which becomes enormously in evidence by reason of thewellknown fact that the tendency to discharge through air from one bodyto another is proportional to the square of the difi'erence of voltagebetween the two bodies, so that whatever be the polarity of the chargein the second body it becomes enormously easier for Then the tendency ofthe negawill be gradually dissipated from the body by' leakage throughthe air; but under ordinary atmospheric conditions as to moisture thisleakage is so slow as to make it inadequate to obviate the diificultywhich is the object of this application to overcome, and T thereforetake advantage of the fact that the tendency of leakage in the case ofelectric charges is proportional to the square of the potential ofthecharges, thus hastening the process in an enormous ratio. The electriccharges on such articles as paper or yarn are sometimes of very highpotential; but they are always of very small quantity, so small, infact, that a single alternation of even a small transformer may providequantity enough to neutralize several square feet of surface of thematerial, and this fact makes it practicable to move the surface of thematerial at a rapid rate past the wire having the alternating charge andstill secure perfect neutralization. A convenient and efiectivealternating potential to use is one that will give about three-fourthsef an inch spark length in air, and by practical experience I find thata wire charged with this potential has a useful range of influenceextending several inches or even a foot each side of the wire, so thateven if we consider the range to be only six inches the velocity of thematerial for perfect neutralization may be anywhere from the very lowestpossible up to a speed at which any given point on the surface of thematerial travels one foot during the time of one cycle or two alternations of the charge on the wire. With a current of sixty cycles persecond, therefore, this would be a speed of one foot in onesixtieth partof a second or sixty feet per second. As a matter of fact if have usedalindicated.

' The invention consists, broadly, of placing a conductor in closeproximity to the charged surface and charging the conductor with analternating potential.

Tn practice I subject the conductor to an alternating current of highvoltage and of standard frequency used incommercial electric lighting.

In a paper-calender, for instance, this may be done by placing a wireacross the face of the rolls at the point where the paper comes off fromthem or at other points where the paper may come in close proximity tothe Wire. The wire is kept charged at a high voltage from atransformercoil delivering an alternating voltage high enough todischarge through the distance which separates the wire from the paper,which may be, for instance, one inch. The paper is thus subjected to arapidly alternating charge which effectually removes all the fixedcharge, leaving the surface of the paper perfectly neutral as it passeson. in a printingpress the wire is stretched across the face of thecylinder at a convenient distance. usually about one inch. lit is notnecessary in carrying out this process that the opposite impulses of thealternating charge should be equal, as T may use, for instance, anordinary inductioncoil, in which the impulses are well known to beunequal in voltage.

ll illustrate my invention-by means of the accompanying drawing, inwhich is shown a diagram of the necessary apparatus for applying myprocess in its preferable form to a web of paper.

Tn the drawing, A represents the alternator, and B the main transformer;C, the condenser; D, the air-gap, and E the secondary transformer of thewell-known Tesla coil, by which an alternating charge of high voltageand high frequency is given to a wire F, which is stretched across inclose proximity and parallel with the face of the web of paper (1.

The wire 15 is so placed with relation to the paper that the charge willpass across from the wire to the paper. As the paper r'noves along'itssurface passes through the rapidlyalternating field thus formed, and asa result the static electricity of the paper is completely neutralized.It is evident that the same process may be readily applied to yarn,roving, and other articles which become charged with static electricityand that any suitable apparatus other than that here shown may be used.

Other means than the wire here shown may be used to receive thealternating charge; but I have found that the process works best when abody with a limited amount of surface, like a wire, is used.

I claim 1. The herein-described method of neutralizing a charge ofstatic electricity in a body by passing it through a field ofalternating static electricity.

2. The herein-described method of neutralizing a charge of staticelectricity in a body by placing it in close proximity to another bodysubjected to an alternating charge of high voltage.

3; The herein-described method of neutralizing a charge of staticelectricity in a body by passing itin close proximity to another IIObody having a relatively small surface and subjected to an alternatingcharge of high voltage.

4. The herein-described method of neutral- 5 izing a charge of staticelectricity in a body by placing it in close proximity to another bodysubjected to an alternating charge of izing a charge of staticelectricity in a body 10 by passing it in'close proximity to a wiresubjected to an alternating charge of high voltage. Signed at Portland,Maine, this 7th day of January, 1904:.

' WILLIAM H. CHAPMAN. Witnesses:

S. W. BATES, L. W. GODFREY.

